In 1827, Robert Brown noticed pollen suspended in water bouncing around erratically. It wasn't until 1905 that Albert Einstein provided an acceptable explanation of the phenomenon (Kac 1947): Brownian motion is the random movement of particles (e.g., pollen) in a fluid (liquid or gas) as a result of collisions with atoms and molecules. Movement of the particles is random. Atoms and molecules move and collide with particles as a consequence of thermal energy defined by temperature. The thermal energy of Brownian motion is necessary to explain the random movement of particles from a high to low concentration (Weiss 2017), the spontaneous movement of a solvent through a membrane (Odom, Barrow, and Romine 2017), the particulate nature of liquids and gases (Wiseman 1979), and movement of particles (such as proteins) within cells. This paper provides a theoretical framework with four associated laboratory activities (Appendix A, Labs 1 through 4) designed to guide construction of knowledge about Brownian motion. Lab 1 involves the direct observation of Brownian motion with a microscope and cell phone camera. Lab 2 guides students to make hypotheses and construct tentative models of random movement of particles based on the experience of a random walk. Lab 3, facilitated by computer technology and Excel software (see "On the web"), provides opportunities for comparisons of multiple models of a random walk, and Lab 4 concludes the instructional sequence with the use of an interactive model of Brownian motion.